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Excessive Fuel Pressure with Mallory 250 Pump

General engine tech -- Drag Racing to Circle Track

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CraigG.
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Excessive Fuel Pressure with Mallory 250 Pump

Post by CraigG. »

Hey Everybody,
My old reliable Mallory (OLD Version) #5250 Comp 250 pump and Mallory Return Style 4300 regulator has worked very well for years. Now had sat for 1+ years and When start the pump it flashes to 9+ PSI and bends the tabs on the floats for 2 seconds to settle down to 6 PSI. I have been using E85 for years and the pump and regulator are gas type and have worked well.

I replaced the regulator diaphragm (by the carb) with the same results. I wonder if the regulator diaphragm on the bottom of the pump has gotten hard and less responsive?

I am stumped.
Thanks, Craig
CraigG.
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Re: Excessive Fuel Pressure with Mallory 250 Pump

Post by CraigG. »

Thanks guys, just wanted to get back to you and let you know the issue was resolved by something very simple and that was the regulator had a vacuum signal port that had been blocked with a vacuum cover – as I thought it was for many years. Once removed to allow the diaphragm to move freely enough to resolve the issue. For everyone who indicated it was simply a regulator issue – You were absolutely right.
I also want to thank RobbMC Performance products for taking the time to help me sort out the issue and also sell me a backup Regulator that works very well for a very reasonable price.
Thanks again everybody, Craig
Kevin Johnson
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Re: Excessive Fuel Pressure with Mallory 250 Pump

Post by Kevin Johnson »

Thank you for following up. =D>
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